1. Field of the Invention
The present invention relates to the field of data communication interfacing, specifically extending the range for communication between computer(s) and remotely located peripherals such as, sensors and receivers.
2. Prior Art
In typical computer-controlled systems, the computer or processor system communicates with remotely located peripheral devices or sensors through industry standardized communications lines. Among those industry standards is the RS-232C standard developed by the Electronic Industry Association (EIA). The various industry standard interfaces available allow the computer or processor devices to communicate with various types and with a plurality of remotely located peripheral devices or sensors.
The practical limitations of the various industry standard interfaces include the number of remotely located peripheral devices that can be communicated with by a single computer or processor device, the distance between the computer and the remotely located peripheral device due to signal attenuation and/or noise, and driving power consumption requirements of the receiving remotely located peripheral device. Accordingly, application of computer/computer-controlled technology can be hampered by such practical limitations. When the requirements of a system or operation exceed the capabilities of a single computer or processor, more units are needed to accomplish those requirements.
When a computer or processor can only communicate with peripheral devices located short distances away, additional computers or processors are required for communicating with those devices that are located long, remote distances away. When a computer or processor device can only communicate with remotely located peripheral devices at a slower speed, the system or operation requires more time to perform a given task. When the transmitting computer or processor must provide driving power to the remotely located peripheral device or when more power must be provided for the peripheral device at its remote location, the system or operation desired becomes more complex and potentially costly.
By overcoming some if not all of these practical limitations, wider application of computer or computer-controlled technology can result in greater efficiency and capacity in a system or operation and can produce substantial cost savings. Fewer computers or processors can be used to control and/or monitor a larger number of remotely located peripheral devices located further away than is possible with the prior art systems. Higher speeds of transmission of data between the computer and the peripheral devices can result in higher efficiencies. No driving power requirements at the remote locations of the remotely located peripheral devices can reduce overall power consumption.
In systems that use RS-232C standard, transmission is typically limited to fifteen meters (approximately 50 feet) at 19,200 baud (similar to bits per second). In some applications, the RS-232C interface standard has been used at a distance of 500 meters (approximately 1600 feet) with a signaling rate of 600 baud.
Usage of RS-232C interface standard is not a problem in a number of applications where typical RS-232C interface connections between computers and peripheral devices have not exceeded the discussed practical limitations. However, there are a number of applications where the desired RS-232C interfacing is not possible with the prior art systems because of the distance and other limitations of the prior art systems.
As an example, in the field of natural gas processing, use of a minimum number of computers or processors to monitor a plurality of remotely located peripheral devices and/or sensors would be desirable. Such application may require the RS-232C interfacing to exceed distances of 1,524 meters (5,000 feet) between a computer monitoring station and a remotely located processing operation or sensor. Use of RS-232C interfacing with its present practical limitations can result in a costly and inefficient system due to the large number of computer stations needed, the relatively lower number of functions performed by each computer, and the corresponding hardware and power requirements of such a system.